We are conducting a randomized, double blind placebo controlled study of surgery with or without raloxifene, EvistaTM for the treatment of pain from endometriosis. This study evaluates whether a selective estrogen receptor modulator, raloxifene, could prevent the regrowth of endometriosis and return of pain in women with pelvic pain from endometriosis. At the first study surgery, all women have laser excision of endometriosis during a laparoscopy. Those with biopsy proven disease are randomized to raloxifene or placebo. Throughout the study women monitor the presence and intensity of various types of pelvic pain, their menstrual cycle, and other symptoms. The effect of raloxifene on the menstrual cycle, lipids, and bone density are monitored. Women are also monitored for mood changes and the occurrence of headaches or deep vein thrombosis. A related goal is to identify non-invasive markers or diagnostic tests for endometriosis. We have accrued 130 women. To date, we have examined the usefulness of MRI in diagnosing endometriosis and correlated histopathology with laparoscopic findings. Our analysis suggests that MRI has limited utility in a cohort of women with pelvic pain because it has a low detection rate of biopsy proven endometriosis lesions and is relatively insensitive in determining whether an individual woman has endometriosis. In comparing surgical and histopathologic findings, only about 70% of endometriosis lesions seen at surgery are biopsy proven. We have identified a greater number of women with endometriosis by staining for the endometrial stromal marker CD10, as it helps to identify endometriosis lesions. In considering markers of endometriosis, we have found that urinary VEGF does not appear to be helpful in determining the presence of endometriosis.